Description
The mineral willemite is a zinc silicate with the chemical formula Zn2(SiO4). It belongs to the nesosilicate family. White, yellow, green, reddish-brown to black, willemite has poor cleavage along crystal planes [0001] and [1120] and a white streak. Its average density is 4.05 and its hardness is 5.5. Its crystal system is trigonal, and the mineral is not radioactive. Willemite is named after the Dutch King William I (1772–1843) by its discoverer, the Brussels-based French mineralogist Armand Lévy (1795–1841). He discovered it in Belgium in 1830, when William I still ruled Belgium, in the Vieille Montagne zinc mine. Willemite is found in metamorphic rocks in the United States and in Tsumeb, Namibia. The type locality is in Franklin, New Jersey, United States. Willemite is mined as a zinc ore. It is mined near the type locality by the American company Franklin and Sterling Hill.
